A very good afternoon to you!

I have an issue with my Simple:Press plugin and simply don't know how to solve this. I have installend S:P on a multi-user Wordpress site and installed it on one of the subsites. However, due to an accident, my Forum-page got deleted and since then, my forum gives a 404 not found error. Is there a way to restore this? 

I tried a clean re-install, but the plugin keeps on finding my old forum, so the same 404-error persists. Thank you so very much for your time and support!